Luke Schneider, head of the completely wireless, smartphone-enabled startup Silvercar, is out to make car rental cool. "We want to be able to turn every Silvercar into your car," he says. "Regardless of the city you're in, you get into your car and your preferences--climate control, radio and seat-positioning settings, itinerary destinations, even favorite restaurants--are already programmed in."

He's not quite there yet, but the road to this goal starts at Silvercar's rental lot at Dallas-Fort Worth International Airport, where 200 identical silver 2013 Audi A4 sports sedans await the company's target market: tech-savvy, independent-minded business and leisure travelers willing to pay $50 to $75 per day for a luxury automobile outfitted with navigation, satellite radio and a Wi-Fi hot spot.

We want to be able to turn every Silvercar into your car.--Luke Schneider

The sweet rides may be the main attraction, but what has really generated loyal fans is Silvercar's attempt to eliminate teeth-grinding lines at the rental counter, annoying upsell pitches and guesswork about which type of car customers will actually get.

Schneider's background as CTO at car-share company Zipcar helped guide the development of Silvercar's iOS and Android apps, which lead customers through the entire rental process, including unlocking the vehicle for them and automatically syncing satellite radio preferences and phone contacts. Dropping off the car is equally simple; the Audi automatically logs mileage, tolls and fuel used.

Silvercar developed its platforms to work specifically with Audi's proprietary software; the auto company was selected for its appeal to both men and women, its smart technology and its user-multimedia interface.

According to Neil Abrams of Abrams Consulting Group, a car-rental consultant firm in New York, Silvercar should be able to carve out a niche within the estimated $10 billion airport-based U.S. rental-car market. The company "is that next step forward," he says. "It's not for everybody, but that's OK. They just need to prove the business model can be profitable."

That model is already gaining traction. Two weeks after launching the service last winter, Silvercar reported its first sellout. The company aims to expand to airports in other major cities by year's end.

Co-founder Bill Diffenderffer calls Silvercar "the big idea that's hiding in plain site." His parking lots full of silver A4s should make it easier for car renters to find.